Pump short cycles

I have a jet pump with an 80 gallon pressure tank, no bladder. The feedback device is all metal (at my other house it is clear plastic). It appears to have a slight leak on the feedback device since there is a lot of minerals and rust on it.

The pump doesn't seem to be acting right, at least in comparison with the similar setup at our other house; when the water is turned on, in just a few seconds the pump kicks on but only runs for about 8 seconds. This repeats over and over until the usage is stopped. I tried to drain the tank (thinking it was waterlogged) but it didn't change anything. However, I'm not sure how much of the tank I was able to drain. The flow rate seems to be fine, of course the pressure rises and falls each time the pump cycles.

I have no idea what you mean by a feedback device. How does air normally get added to the tank? Draining the tank is not how to add air. Even if you managed to drain it completely and got it to be full of air, it would not be enough air once compressed. Some folk use an air compressor to top up the air.

I used the term "feedback device" because I don't know the plumbing term. It's mounted on the side of the tank and has a tube that goes back to the pump/motor assembly, so I assume it tells the motor/pump when to turn on or off.

How is the best way to get air into the tank once I drain it? There's a plug on the top of the tank, could I put a fitting on there?

I have found that the best way to fully drain that type of tank is to kill power to the pump and Remove the air volume control then open the output and let it drain until the water stops completely.

I removed my AV100 because I got tired of it not working or lasting very long.

I put a plug in its place, and just remove the plug and drain the tank every 4 months or so.
That also lets me flush the tank. I do not add any air. The plug just needs to be installed before turning the pump back on.

I found that the Air Volume controls do not work very well or long. They were a PITA for me.

That under-utilizes the size of tank and will not give you the best drawdown. It is marginal at best and just gets worse over time.

Many people will put a schrader valve in the place of the pressure gauge or Tee it in beside the gauge if there is one on the AVC. Then they just add air periodically.

I have a composite WellMate precipitation tank for my iron filter so the tank gets its air from a miconizer. If/when I have to drain the tank, I will top up the air with my compressor rather than have the micronizer slowly add the needed air.

The ideal volume of air would have the tank nearly empty of water at the kick-in pressure. I have personally never witnessed an AVC regulate the volume to just 25%. Most float type AVCs are about midway up the side of the tank. Whatever engineer designed your tank should not be allowed to wear his pinky ring.

Seems to me if you are only using half the Tank Volume to hold the water then, You are wasting large amounts of tank space.

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Huh? The amount of water that is in the tank at kick-in pressure is wasted space since the only way you will ever get to use it is to open the drain cock and capture it in a pail.

The only useful water is that which is between the kick-in and kick-out pressures. Look at how a bladder tank works. It is nearly empty at kick-in. Some of the newer hydropnuematic tanks that claim to have near the same drawdown as bladder tanks do so by having more air and less water in them.

People still want to buy those huge hydropnuematic tanks thinking they have more water in storage. Pfft! Ja, dead storage.

Huh? The amount of water that is in the tank at kick-in pressure is wasted space since the only way you will ever get to use it is to open the drain cock and capture it in a pail.

The only useful water is that which is between the kick-in and kick-out pressures. Look at how a bladder tank works. It is nearly empty at kick-in. Some of the newer hydropnuematic tanks that claim to have near the same drawdown as bladder tanks do so by having more air and less water in them.

People still want to buy those huge hydropnuematic tanks thinking they have more water in storage. Pfft! Ja, dead storage.

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BIG Difference in a Bladder Tank.

This type of tank does not have a Bladder, That is why a AVC is used.

I am no expert on Water Well Systems, Only Rocket. I just believe what I see.

Thought I would post an update on my short cycling problem; I replaced the old AVC-45 with the Sears AVC which is a clear plastic bowl with a check-ball valve in it. I opened the drain on the tank and after a while I removed the old AVC. Apparently the tank was almost completely waterlogged and took a while to empty out. I installed the new AVC and turned on the pump and it came up to pressure in just a few minutes and now cycles just fine. The only thing I noticed about my installation is that the pump outlet is a little higher than the input to the tank, i.e. it pumps "downhill". I was concerned that I might lose prime but that didn't happen.

Thanks again to the guys who replied on this thread, and thanks to Terry Love for maintaining such a useful forum.